1. Field of the Invention
The invention generally relates to a press-in spring contact connector suitable for press-in installation into bores of a printed circuit board. More particularly, the present invention relates to a connector having contact springs manufactured from sheet metal wherein the contact springs are secured in an insulator in a manner that the contact springs have sufficient strength to withstand a press-in operation.
2. Description of the Prior Art
Spring contacts are known for use in solder-free press-in connectors. Generally, spring contact connectors have a plurality of contact springs secured in a plastic insulator. In known connectors, each contact spring is configured to have a press-in portion extending from the insulator, the press-in portion being configured for male insertion into contact bores of a printed circuit board. Opposite the press-in portion, known contact springs also have a contact part which is enclosed by the insulator. The contact part can be a female contact portion configured to receive a generic male connector after the spring contact connector has been installed on a printed circuit board.
For example, German Letters Patent 37 00 304, incorporated by reference herein, discloses a spring contact connector wherein a contact spring has a contact part configured as a double contact for receiving a male member into biased contact between two points. The contact spring is formed as a blade shape having a region extending downward for press-in contact. This prior art contact spring is also arranged and secured in a chamber formed between two insulator members. The contact spring has a middle region with outer edges which form a fastening section. The fastening section is clamped between the insulator members so that an interlocking occurs between shoulders extending from the outer edges and the insulator members.
Also, German application DE 92 13 611, incorporated by reference herein, discloses a press-in portion of a spring contact connector configured for optimal contact within a bore.
Traditionally, a press-in installation operation of a connector into the bores of a printed circuit board is performed by an insertion press. In prior art insertion presses, a plurality guide pins are inserted into the respective spring contacts to hold the connector. Subsequently, pressure is exerted to insert the connector into the bores. Shoulders, hooks or notches in prior art spring contacts have been provided to engage and transmit some of the press-in forces to the surrounding insulator walls. The force required to adequately press a connector into bores of a printed circuit board can be up to 120 N.
Contact springs can be damaged by the prior art press-in technique. Because press-in connectors can be small, the contact springs are rather fragile and are easily susceptible to buckling or abrasion damage. The delicate contact springs are sometimes coated with gold to provide improved contact for precision applications, such as data transmission. On the other hand, guide pins on an insertion press are usually not coated with a precious metal, as such a design would be cost prohibitive. Therefore, the mere insertion and retraction of guide pins can damage the spring contacts through abrasion.
Also, an insertion press must be constructed with a high degree of precision. If a guide pin is misaligned, insertion of the guide pin can crush a contact spring, requiring the removal of the entire connector from an assembly line.
Furthermore, a contact spring must have sufficient rigidity so that it will not deform or buckle from the loads on the press-in parts during their insertion into the bores. Therefore, the contact springs and the surrounding insulator structure are desirably complementarily designed to carry such loads using minimal material.
Spring contact connectors are available in a multitude of types having various numbers of contact springs. A corresponding insertion press must be provided which is suitable for each respective type. According to the prior art installation technique, an insertion press for use with a connector having a large number of contacts can have many guide pin components and appear something like a board of nails. In view of the necessary precision and the multitude of types required to match the various connector configurations, the insertion presses are complicated and cost-intensive tools, both for manual and automatic presses.
Therefore, a need exists for a press-in spring contact connector in which the contact springs can sufficiently carry a press-in load without deformation or buckling. A need also exists for a method of installing such a connector wherein the method minimizes a risk of damage to the spring contacts.